Damn it where's 7th gear when you need it?!
Dont bother with Kwik Fit, too commercial and staffed by too many children & not enough experienced people. Find yourself a big local independant tyre fitter, one that has queues down the road on a saturday morning & loads of flashy kit! Basically you need some super-accurate measuring machine to test all the alignments & re-check the balancing. Yes the convertible will be a little washy incomparison to the hard top variants when you push them hard but nothing like what your describing.
A4 3.0 Quattro Sport - Gone & missed everyday!
Current road going missile.....
........Smart Roadster - arguably the most fun you can have in a car without using lube!!